Polyethylene terephthalate resins with their excellent mechanical and electrical properties have been widely used to date as materials of fibers, films and the like and also as molding materials. Since their mechanical properties and thermal properties are largely improved when they are admixed with reinforcing fibers especially glass fiber, hence the reinforced resin compositions so obtained are suited for use as materials of so-called functional parts.
In recent years, there has been a growing demand for safety against fire especially in the field of electric or electronic parts and, to meet such demand, effort has been made for impartation of flame retardance to resins by addition of organic halogen compounds or high-molecular halogen compounds. A portion of electric and electronic parts for which such flame-retardant materials are used includes members, which are brought into direct or indirect contact with water or water vapor, and in such a field a high wet heat resistance, which means capability of preventing sudden lowering of mechanical strength even under high temperature and high humidity conditions, is required, in addition to high flame retardance.
As to flameproofing of thermoplastic polyester, there have been proposed a method of adding a halogenated polystyrene resin as disclosed in, for example, Laid-open Patent Publication No. 92346/'75, methods of adding halogenated epoxy resin in Laid-open Patent Publication No. 35257/'75 and Laid-open Patent Publication No. 15256/'87 and a method of adding high polymer halogenated phenoxy resin in Laid-open Patent Publication No. 149954/84.
Further, for improving flame retardance and also its resistance to moisture, a method of adding a high-molecular halogenated and copolymerized phenoxy resin together with an epoxy compound and/or a carbodiimide compound as disclosed in Laid-open Patent Publication No. 129253/84.
When a halogenated polystyrene resin, a halogenated phenoxy resin and the like as mentioned above are used as flame retardants, there are problems with regard to dispersibility thereof in polyethylene terephthalate resins or their individual flow properties (fluidity), while, when the halogenated epoxy resin is used, the flow property at a high temperature is deteriorated due to its reactivity with the polyethylene terephthalate and, in addition thereto, there is a problem of the added resin tending to bleed on the surface of molded articles when heated. Thus, problems are likely to occur about moldability, mechanical strength and surface characteristics.
Further, with regard to the demand for high wet heat resistance, addition of an epoxy compound or a carbodiimide compound alone is insufficient.
The object of the present invention is, therefore, to obtain a polyethylene terephthalate resin composition to which flame retardance is imparted without deterioration of moldability and mechanical strength and which is also improved in wet heat resistance.
After extensive and intensive studies, the present inventors have found out that the aforementioned object can be attained by the use of a polyethylene terephthalate resin produced with a germanium compound as a catalyst, and by the addition of a halogen flame retardant and the specific class of compounds or by the addition of a halogenated epoxy resin, and thus arrived at the present invention.